Expert: Philip Stahl - 8/23/2006

Question
Hi,

I was reflecting on the following part of your answer

“As I already noted, any hypothetical sound or pressure wave that might begin - can't last since there's not the medium to sustain its propagation.”

I have a question now.

Is it possible that the hypothetical sound or pressure wave could get converted into the medium?

Energy and matter are interchangeable. Whether the continued pressure wave get converted into particles and then formed as molecules (medium)? Can we say the origin of air is these pressure waves?

Hope you can share your views on this.

Thanks,
Raja


Answer
Hello.

It is certainly possible that hypothetical sound or pressure waves can be converted into energy (e.g. heat) in the medium. But not into the medium itself.

Energy and matter (mass) are interchangeable but only at the atomic level. (e.g. via Einstein's equation, E = mc^2) No one has yet figured out any way for transmuting energy into mass at the normal molecular level - at least that I know of.

The origin of the Earth's air (atmosphere) evolved from the chemical interplay of the solid and fluid Earth over geological time scales. Thus, the Earth's original atmosphere had NO air at all - but rather mostly sulphur dioxide, hydrogen, methane (CH4) and ammonia (NH3). This was a direct result of the volcanism at the time of the primitive Earth - which spewed these gases out in abundance.

Over time, ultraviolet light (short wavelength EM radiation) penetrated and broke up the methane, ammonia and water vapor. Hydrogen - as the lightest component molecule- escaped into space. (Its escape velocity exceeded the gravitational pull of Earth)

Some of the oxygen liberated from the H20 combined with carbon from the methane and gradually eliminated elemental carbon. Some of the oxygen atoms eventually formed the ozone (O3) layer that now protects us against UV radiation.  Nitrogen then became the primary constituent of the atmosphere - having been liberated from the NH3.

In none of this did any sound or pressure waves play a role - rather chemical evolution in the planetary environment.

Oxygen was added to the N2 in the atmosphere, as biological life forms multiplied - which generated large amounts of O2, e.g. in respiration.

Hopefully, this will explain more of what is going on.